Inventory Reserve
An accounting write-down, or FBA units temporarily unavailable to sell.
Definition
Inventory reserve has two meanings sellers run into. In accounting it is a balance-sheet allowance that writes down the value of stock you expect to become unsellable; in Amazon's FBA dashboard, reserved inventory is units that exist in the network but are temporarily unavailable to sell.
The accounting meaning: a reserve for unsellable stock
In plain terms, this is a formal way of telling your books that some inventory is probably not worth what you paid for it. Technically it is a contra-asset allowance that reduces the carried value of stock you expect to lose to obsolescence, damage, or a drop in market value, recognizing the loss before the actual write-off so your inventory valuation stays honest instead of optimistic.
The Amazon meaning: reserved (unavailable) units
In Seller Central, reserved units are real inventory that is temporarily not sellable, because it is tied to a pending customer order, in transfer between fulfillment centers (FC transfers), or being processed at a center. The one that surprises sellers is FC transfers, which can sit in reserved for one to three weeks and quietly shrink your sellable count right when you are planning a restock.
Why the FBA reserved bucket matters for your restock decisions
Your sellable count is lower than your total on-hand by whatever sits in reserved. Plan cover against what can actually fill demand now, so a large reserved bucket does not trick you into thinking you have more runway than you really do.
Related terms
Plan against what is actually sellable
Inventory Hero separates sellable from reserved and in-transit units, so your days of cover reflect what can really fill an order today.